Egress

Question

Can a newly constructed dwelling have one means of egress if constructed according to 780 CMR, the Massachusetts State Building Code?

Discussion

The BOCA '93 model code includes R-3 as a building type in which only one means of egress is required (BOCA '93 1010.3). Massachusetts has specifically deleted this provision (780 CMR 1010.3). Nevertheless an argument can be constructed based on other references in Chapter 10 (Means of Egress) of 780 CMR, that a single means of egress is justifiable in terms of specific code references.

This line of thought begins with section 1010.0 NUMBER OF EXITS. Paragraph 1010.2 Minimum number, states: "Every floor area shall be provided with the minimum number of approved independent exits as required by Table 1010.2 based on the occupant load, except as modified in 780 CMR 1010.3."

The application of this section to multi-family apartment buildings with common corridors is such that any given dwelling unit need only have one egress door as long as there are a minimum of two means of egress from the floor, and all other applicable sections of 780 CMR are met (remoteness, travel distance, occupancy load, etc.).

1010.2 concludes with the following exception: "In buildings with occupancies in Use Group R having multistory dwelling units, the means of egress from a dwelling unit to the required exits is permitted to be provided from one level only. Within the dwelling unit access to the means of egress from the unit shall conform to the applicable provisions of 780 CMR 10."

The principal "applicable provision" referred to here is section 1017.2, Spaces with One Means of Egress. In this section Use Group R, with a maximum occupant load of 10 and a maximum travel distance of 75', is among the uses where such spaces are permitted.

Based on the above, a multistory dwelling unit with a maximum travel distance of 75' and a maximum occupant load of 10 people can have only one exit door, as long as the floor onto which this exit door opens has the required number of exits (typically a minimum of two).

In summary, a residential building must have two means of egress, but each residential unit within that building is not required to have more than one means given the conditions described above. Can these provisions be extended to a building with three-story townhouses, each with one independent means of egress, if the travel distances and minimum occupant loads for each unit meet the conditions of Table 1017.2? Diagrammatically the townhouse layout could be identical to the apartment layout allowed under exception 1010.2, with the exception that instead of discharging into an egress corridor the townhouse exit discharges directly to the outside. If the townhouse is part of an R-2 structure then the residential building would have the minimum required number of exits (one per unit would always exceed the requirements of Table 1010.2). If the townhouse is classified as R-3, multiple single family, section 310.5 (Use Group R-3 structures) requires that "each unit has an independent means of egress..."(emphasis added).

The BBRS has declined to issue any comment on this question. It is likely that the Massachusetts State Building Code does not contain language which specifically addresses this townhouse condition.
P>The BOCA '93 model code includes R-3 as a building type in which only one means of egress is required (BOCA '93 1010.3). Massachusetts has specifically deleted this provision (780 CMR 1010.3). Nevertheless an argument can be constructed based on other references in Chapter 10 (Means of Egress) of 780 CMR, that a single means of egress is justifiable in terms of specific code references.

This line of thought begins with section 1010.0 NUMBER OF EXITS. Paragraph 1010.2 Minimum number, states: "Every floor area shall be provided with the minimum number of approved independent exits as required by Table 1010.2 based on the occupant load, except as modified in 780 CMR 1010.3."

The application of this section to multi-family apartment buildings with common corridors is such that any given dwelling unit need only have one egress door as long as there are a minimum of two means of egress from the floor, and all other applicable sections of 780 CMR are met (remoteness, travel distance, occupancy load, etc.).

1010.2 concludes with the following exception: "In buildings with occupancies in Use Group R having multistory dwelling units, the means of egress from a dwelling unit to the required exits is permitted to be provided from one level only. Within the dwelling unit access to the means of egress from the unit shall conform to the applicable provisions of 780 CMR 10."

The principal "applicable provision" referred to here is section 1017.2, Spaces with One Means of Egress. In this section Use Group R, with a maximum occupant load of 10 and a maximum travel distance of 75', is among the uses where such spaces are permitted.

Based on the above, a multistory dwelling unit with a maximum travel distance of 75' and a maximum occupant load of 10 people can have only one exit door, as long as the floor onto which this exit door opens has the required number of exits (typically a minimum of two).

In summary, a residential building must have two means of egress, but each residential unit within that building is not required to have more than one means given the conditions described above. Can these provisions be extended to a building with three-story townhouses, each with one independent means of egress, if the travel distances and minimum occupant loads for each unit meet the conditions of Table 1017.2? Diagrammatically the townhouse layout could be identical to the apartment layout allowed under exception 1010.2, with the exception that instead of discharging into an egress corridor the townhouse exit discharges directly to the outside. If the townhouse is part of an R-2 structure then the residential building would have the minimum required number of exits (one per unit would always exceed the requirements of Table 1010.2). If the townhouse is classified as R-3, multiple single family, section 310.5 (Use Group R-3 structures) requires that "each unit has an independent means of egress..."(emphasis added).

The BBRS has declined to issue any comment on this question. It is likely that the Massachusetts State Building Code does not contain language which specifically addresses this townhouse condition.